Fir Seedlings Research Articles

Dermal absorption of triclosan following short- and long term exposure in an ex vivo human skin model

Although advance regeneration abundance and vigor are critical factors determining future forest composition and productivity, very few studies have focused on how they are affected by spruce budworm (SBW) outbreaks even though they affect millions of hectares of boreal forest on a cyclical basis. Post-SBW salvage logging is often used to reduce economic losses but could interact with the outbreak to affect advance regeneration. This study aims to determine the impact of SBW outbreaks and post-outbreak salvage logging on the defoliation of advance regeneration in mixed coniferous stands of northeastern Canada. Specifically, we assessed the effect of regeneration height and species (balsam fir or black spruce), as well as canopy composition, on the defoliation of advance regeneration. We then evaluated the effect of salvage logging on defoliation sustained by advance regeneration and compared it to the one observed in stands only affected by the SBW. Regeneration height and species, canopy composition and salvage logging all significantly affected defoliation and showed multiple interactions. Taller balsam fir seedlings were three times as defoliated as smaller ones, whereas it was 2.3 times for black spruce. Balsam fir seedlings were 15% more defoliated than black spruce. Seedlings of both species located beneath a balsam fir canopy were also more defoliated (>50% defoliation) than seedlings found under black spruce trees (about 26% defoliation). Salvage logging in black spruce-dominated stands resulted in a ∼25% increase in defoliation of tall (2.5 m) black spruce regeneration when compared to non-harvested sites. We speculate that this could increase the fir component in spruce-dominated stands, leading to forests that are more susceptible to future SBW outbreaks. To protect spruce advance regeneration from increased defoliation, salvage harvesting of spruce-dominated stands may thus be delayed until the outbreak has subsided. Long-term studies are needed to determine whether a compositional change occurs or not, particularly in spruce-dominated stands. As a precautionary measure, changes in salvage logging practices may be implemented immediately to avoid potential problems such as decreased black spruce abundance and increased susceptibility to future SBW outbreaks.

Deer browsing outweighs the effects of site preparation and mechanical release on balsam fir seedlings performance: Implications to forest management

Abstract High abundance of large herbivore has major impacts on the composition, structure, and functioning of forest ecosystems, which can result in regeneration failures. Reduction of large herbivore density, however, does not warrant the successful establishment of tree species sensitive to browsing. In such contexts, planting in combination with silvicultural treatments can be used to restore forest cover over large areas. Using an experimental plantation on Anticosti Island (Quebec, Canada), we investigated how white-tailed deer ( Odocoileus virginianus ) browsing affects the performance of planted balsam fir ( Abies balsamea L. Mill.) seedlings following site preparation and mechanical release. After seven growing seasons, seedling height, leader length and ground-level diameter were 30% bigger in fenced plots compared to unfenced ones as a result of cumulative browsing. Seedling survival was low (62%) and unaffected by either silvicultural treatments or deer after the onset of the mechanical release treatment. Site preparation and mechanical release did not improve morphological parameters and did not increase browsing occurrence on fir, likely because they had little influence on surrounding plants that compete for resources and may hide seedlings from deer 7 years after planting. Selective browsing on neighbouring plants also acted as a release treatment for balsam fir seedlings, allowing them to reach full sunlight at a lower height (125–146 cm), compared to fir seedlings in deer exclosures (161–184 cm). We propose that managers aim at target deer densities that promote browsing positive effects. In such context, prescription for site preparation and mechanical release should be based on other considerations than promoting seedling growth, such as facilitating practical reforestation work.

Structure and Composition of a Dry Mixed-Conifer Forest in Absence of Contemporary Treatments, Southwest, USA

Dry mixed-conifer forests in the Southwest occupy an important ecological and hydrological role in upper watersheds. In the absence of reoccurring fire and silvicultural treatments over the last 50 years, we quantified forest structure and composition on prevailing north and south aspects of a dry mixed-conifer forest in southcentral New Mexico using mixed models and ordination analysis in preparation for an experiment in ecological restoration. Results indicated overstory and midstory were dominated by Douglas-fir (Pseudotsuga menziesii) and shade tolerant/fire intolerant white fir (Abies concolor) with interspersed mature aspen on north aspects, and Douglas-fir and Southwestern white pine (Pinus strobiformis) on south aspects. Ponderosa pine (Pinus ponderosa), which was historically co-dominant with Douglas-fir on north and south aspects, was subdominant on south aspects and almost entirely absent on north aspects. Regeneration was dominated by white fir saplings and seedlings on north aspects while ponderosa pine was completely absent. South aspect saplings and seedlings were characterized by Douglas-fir and Southwestern white pine, but almost no ponderosa pine. Ordination analysis characterized the effect of aspect on species composition. Understanding contemporary forest structure and composition is important when planning for desired future conditions that are to be achieved through ecological restoration using silvicultural techniques designed to foster resilience.

Excessive Accumulation of Chinese Fir Litter Inhibits Its Own Seedling Emergence and Early Growth—A Greenhouse Perspective

Litter accumulation can strongly influence plants’ natural regeneration via both physical and chemical mechanisms, but the relative influence of each mechanism on seedling establishment remains to be elucidated. Chinese fir (Cunninghamia lanceolata) is one of the most important commercial plantations in southern China, but its natural regeneration is poor, possibly due to its thick leaf litter accumulation. We used natural and plastic litter to study the effects of Chinese fir litter on its own seedling emergence and early growth, as well as to assess whether the effect is physical or chemical in nature. Results showed that high litter amount (800 g·m−2) significantly reduced seedling emergence and the survival rate for both natural and plastic litter. Low litter amount (200 g·m−2) exerted a slightly positive effect on root mass, leaf mass, and total mass, while high litter amount significantly inhibited root mass, leaf mass, and total mass for both natural and plastic litter. Root-mass ratio was significantly lower, and leaf-mass ratio was significantly greater under high litter cover than under control for both natural and plastic litter. Although the root/shoot ratio decreased with increasing litter amount, such effect was only significant for high litter treatment for both natural and plastic litter. Seedling robustness (aboveground biomass divided by seedling height) decreased with increasing litter amount, with high litter treatment generating the least robust seedlings. Because plastic and natural litter did not differ in their effects on seedling emergence and growth, the litter layer’s short-term influence is primarily physical. These data indicated that as litter cover increased, the initial slightly positive effects on seedling emergence and early growth could shift to inhibitory effects. Furthermore, to penetrate the thick litter layer, Chinese fir seedlings allocated more resources towards stems and aboveground growth at the expense of their roots. This study provided experimental evidence of litter amount as a key ecological factor affecting seedling development and subsequent natural regeneration of Chinese fir.

Differences in bud burst timing and bud freezing tolerance among interior and coastal seed sources of Douglas fir

Key messageThe Douglas fir provenance Three Valley was found most suitable for planting in mid-Sweden. Greenhouse tests can most likely predict how different Douglas fir provenances will perform in the field.The need for species that will grow well through ongoing climate change has increased the interest in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] in Sweden. One of the most common problems seen in plantations of Douglas fir seedlings is damage caused by late spring frost, known to be highly correlated with the timing of bud burst. The objective of this study was to investigate spring-related bud development under Nordic conditions of seven Douglas fir provenances and to compare data with a local provenance of Norway spruce (Picea abies (L.) Karst). Results from a field trial and a greenhouse-based study were compared. The interior Douglas fir provenances exhibited an earlier bud burst than coastal provenances, both in the greenhouse and in the field trial. When comparing differences within the groups of interior and coastal Douglas fir provenances, no differences could be found. The local Norway spruce, only grown in the greenhouse, showed an intermediate bud development profile similar to the interior Douglas fir provenance Three Valley. We therefore suggest that Three Valley could be planted at the same locations as the investigated local provenance of Norway spruce in mid-Sweden. To avoid spring frost damage the Douglas fir seedlings need to be frozen stored and planted late in spring. Planting under shelterwood can also help protect the seedlings from spring frost damages. As similar results for bud development patterns of Douglas fir and Norway spruce provenances were obtained from the greenhouse and field trials, greenhouse tests could facilitate selection of provenances.

Disturbance in seedling development of Korean fir (Abies koreana Wilson) tree species on higher altitude forests of Mt. Hallasan National Park, the central part of Jeju Island, Korea

BackgroundNatural regeneration of seedlings as well as saplings of Korean fir has been significantly impacted by the browsing from the early stages of their development, potentially, by roe deer for the last two to three decades at the study site since late 1980s. This study was carried out to investigate current status of the disturbance in the seedling development of Korean fir (Abies koreana) on Mt. Hallasan, Jeju Island, Korea.MethodsField survey was carried out during June and August in 2016 to measure the characteristics of study site and understory vegetation by applying systematic sampling to 125 plots of 5 m × 5 m quadrat located on eastern slope of the mountain. Correlation and regression analyses were applied to the variables quantified from the data sets using the SAS software.ResultsNo saplings with their diameters at breast heights smaller than 5.0 cm were found at the study site indicating the serious disturbance in the natural regeneration of Korean fir at the study site. No seedlings with their heights taller than 36.0 cm were found at the study site indicating even more serious disturbance during earlier stage of the natural regeneration of Korean fir at the study site. A total of 616 individuals of the seedlings of Korean fir were found at 54 out of 125 sampling plots. One hundred thirty-eight seedlings (22.4%) out of 616 individual seedlings have the vestiges for being grazed, potentially, by roe deer.ConclusionsDue considerations should be given to the effects of browsing of the seedlings by roe deer to promote the natural regeneration of Korean fir, ultimately to restore Korean fir. It is needed for the managers of the forest to install fences around the forest area. Exclosure experiments as well as enclosure experiments of different densities of browsing should be carried out. In addition, treatment with different densities of Jeju dwarf bamboo should also be included in the experiment on Mt. Hallasan National Park, Jeju Island, Korea.

Survival and growth of naturally regenerating Sakhalin fir seedlings after clear cutting of planted fir forest

Survival and growth of naturally regenerating Sakhalin fir seedlings after clear cutting of planted fir forest

Ectomycorrhizal fungal communities of silver-fir seedlings regenerating in fir stands and larch forecrops

Key messageThe diversity of ECM communities of 1-year-old silver-fir seedlings regenerating in mature silver-fir stands is significantly higher than in neighboring larch forecrops.Forecrop stands provide the necessary shade for shade preferring seedlings, such as silver-fir, which cannot be introduced as the first generation in open areas. Larch is a good candidate, recommended to be utilized as forecrop. Since fungal symbionts of Abies alba seedlings regenerating under larch canopy have not been investigated, we aimed to evaluate the diversity of ECM of 1-year-old silver-fir seedlings regenerating under canopy of larch and to compare these communities to those found in adjacent mature silver-fir stands. Three silver-fir stands (F) and three European larch forecrops (L) were selected to study. Seedling size did not differ between F and L stands. ECM colonization was observed in 100% silver-fir seedlings in F and 80% in L stands. The fine roots were highly colonized, and 91 and 87% of live ECM were found in seedlings from F and L stands, respectively. Sequencing analysis revealed a total 53 ECM taxa. The observed number of ECM taxa in the F stands was significantly higher (46) than that in the L forecrops (25), and 34% of taxa were common to both stands. The dominant ECM species in F were unidentified fungus 1, Piloderma sp., Tylospora asterophora and Russula integra. Fir seedlings regenerating in L forecrops formed ectomycorrhizas mostly with unidentified fungus 1, Tomentella sublilacina, Tylospora sp., Hydnotrya bailii and T. asterophora. Based on ANOSIM analysis, ECM communities have shown significant differences between study sites. The diversity of ECM fungal partners and the high colonization rate of silver-fir seedlings regenerating in larch forecrop stands should be sufficient to provide efficient afforestation of post-arable lands and gives the opportunity for their successful rebuilding.

模拟氮沉降对杉木幼苗细根的生理生态影响

模拟氮沉降对杉木幼苗细根的生理生态影响

土壤增温对杉木幼苗细根生理生态性质的影响

土壤增温对杉木幼苗细根生理生态性质的影响

土壤增温、隔离降水及其交互作用对杉木幼苗细根生产的影响

土壤增温、隔离降水及其交互作用对杉木幼苗细根生产的影响

杉木幼苗和伴生植物细根对土壤增温的生理生态响应

杉木幼苗和伴生植物细根对土壤增温的生理生态响应

Studies on tissue water relations and soluble sugars in Cilician Fir (Abies cilicica) seedlings during bud dormancy

Studies on tissue water relations and soluble sugars in Cilician Fir (Abies cilicica) seedlings during bud dormancy

Interactive effects of soil warming and nitrogen addition on fine root production of Chinese fir seedlings

Interactive effects of soil warming and nitrogen addition on fine root production of Chinese fir seedlings

Survival and growth as measures of shade tolerance of planted western redcedar, western hemlock and amabilis fir seedlings in hemlock-fir forests of northern Vancouver Island

We examined two measures of shade tolerance (survival and growth) of planted 1-year-old seedlings of western redcedar (Thuja plicata (Donn ex D. Don)), western hemlock (Tsuga heterophylla ([Raf.] Sarg.)) and amabilis fir (Abies amabilis ([Dougl. ex Loud] Dougl. ex Forbes)). Seedlings were planted at two different sites (forest interior: 4.5% mean above canopy photosynthetically active radiation [ACPAR], and forest edge: 41.5% mean ACPAR), in a 90-year-old, windthrow origin, unmanaged mesic western hemlock-amabilis fir stand. Seedlings were planted in 1997, and re-measured in 1998 and 2001 (after five growing seasons). To assess the effects of deer browsing on redcedar survival and growth, additional seedlings of this species were planted and protected with Vexar© tubes. To examine for nutrient-light interactions, half of these seedlings were fertilized with N-P-K and micronutrients at planting. Western redcedar had high levels of survival after 4years (98% in edge plots and 93% in interior plots). Redcedar seedlings in edge plots were more vigorous but were browsed more heavily than in the interior plots. At edge sites, the negative effects of the Vexar© tubes may have been lower than their positive effects. Hemlock survival was about 50% in the stand interior but 80% in the edge plots. Amabilis fir in the interior plots had the lowest survival of the three species, with only 40% of initial seedlings surviving over the next four years, but had high survival in edge plots (95%). Height, biomass, and root collar diameter growth were significantly higher in edge plots for fir and hemlock. However, for redcedar, only biomass was significantly higher and no differences were detected for height and diameter. Our results show that shade tolerance cannot be assessed by simple measures of leaf/light relationships alone, but also requires consideration of light, nutrition, growth and browsing.

Early-successional ectomycorrhizal fungi effectively support extracellular enzyme activities and seedling nitrogen accumulation in mature forests.

After stand-replacing disturbance, regenerating conifer seedlings become colonized by different ectomycorrhizal fungi (EMF) than the locally adapted EMF communities present on seedlings in mature forests. We studied whether EMF species that colonized subalpine fir (Abies lasiocarpa) seedlings in clearcuts differed from those that colonized seedlings in adjacent mature forests with respect to mycorrhizoplane extracellular enzyme activities (EEAs) and N status of the seedlings. We tested two alternate hypotheses: (1) that EEAs would differ between the two EMF communities, with higher activities associated with forest-origin communities, and (2) that acclimation to soil environment was considerable enough that EEAs would be determined primarily by the soil type in which the ectomycorrhizas were growing. Naturally colonized fir seedlings were reciprocally transplanted between clearcuts and forests, carrying different EMF communities with them. EEAs were influenced more by destination environment than by EMF community. EEAs were as high in early-successional as in late-successional communities in both destination environments. Buds of clearcut-origin seedlings had the same or higher N contents as forest seedlings after a growing season in either environment. These results indicate that (i) symbiotic EMF and/or their associated microbial communities demonstrate substantial ability to acclimate to new field environments; (ii) the ability to produce organic matter-degrading enzymes is not a trait that necessarily distinguishes early- and late-successional EMF communities in symbiosis; (iii) early-successional EMF are as capable of supporting seedling N accumulation in forest soils as late-successional EMF; and (iv) disturbed ecosystems where early-successional EMF are present should have high resilience for organic matter degradation.

Role of geographical provenance in the response of silver fir seedlings to experimental warming and drought.

Changes in climate can alter the distribution and population dynamics of tree species by altering their recruitment patterns, especially at range edges. However, geographical patterns of genetic diversity could buffer the negative consequences of changing climate at rear range edges where populations might also harbour individuals with drought-adapted genotypes. Silver fir (Abies alba Mill.) reaches its south-western distribution limit in the Spanish Pyrenees, where recent climatic dieback events have disproportionately affected westernmost populations. We hypothesized that silver fir populations from the eastern Pyrenees are less vulnerable to the expected changing climate due to the inclusion of drought-resistant genotypes. We performed an experiment under strictly controlled conditions simulating projected warming and drought compared with current conditions and analysed physiology, growth and survival of silver fir seedlings collected from eastern and western Pyrenean populations. Genetic analyses separated eastern and western provenances in two different lineages. Climate treatments affected seedling morphology and survival of both lineages in an overall similar way: elevated drought diminished survival and induced a higher biomass allocation to roots. Increased temperature and drought provoked more negative stem water potentials and increased δ13C ratios in leaves. Warming reduced nitrogen concentration and increased soluble sugar content in leaves, whereas drought increased nitrogen concentration. Lineage affected these physiological parameters, with western seedlings being more sensitive to warming and drought increase in terms of δ13C, nitrogen and content of soluble sugars. Our results demonstrate that, in A. alba, differences in the physiological response of this species to drought are also associated with differences in biogeographical history.

Storability and freezing tolerance of Douglas fir and Norway spruce seedlings grown in mid-Sweden

ABSTRACTClimate change provides new challenges to Nordic forestry. Use of non-native species, such as Douglas fir, can be a means of mitigating the effects of climate change and meeting the growing demand for biomass. When Douglas fir is grown in Sweden, it is several degrees of latitude north of its normal range, which can affect timing of growth cessation, hardening of seedlings, and seedling storability. The objective of this study was to investigate tolerance to freezing and sub-zero storability of seven Douglas fir provenances and make comparisons with the native Norway spruce. Freezing tolerance and storability were evaluated by measuring the electrolytic leakage of shoots and roots after freezing, complemented with a three-week cultivation test after storage. All provenances of Douglas fir used in this study were able to tolerate frozen storage at −4°C for about four months. Norway spruce and the interior Douglas fir provenance, Three Valley, could be stored earlier in the autumn than the southern coastal Douglas fir provenances. Consequently, it should be possible to store Douglas fir seedlings with the same routines as for Norway spruce.

Effects of soil warming and nitrogen addition on the length distributions of different diameter class fine roots of Chinese fir seedlings.

In order to determine how the diameter class length distribution (DCLD) of fine roots of Chinese fir (Cunninghamia lanceolata) would be affected by soil warming, nitrogen addition and their interaction, a factorial experiment of soil warming (ambient, +5 ℃) and nitrogen addition (ambient, +4 and +8 g N·m-2·a-1) was carried out in the Chenda State-owned Forest Farm in Sanming, Fujian Province. An expanded extreme value model fitted the DCLD of roots of all the six treatments very well (R2=0.97). The model parameters showed that soil warming reduced the total root length, but its effect on root diameter was not significant. Nitrogen addition decreased both total root length and root diameter. The interaction of soil warming and nitrogen addition had significant effects on total root length, but had no significant effects on root diameter. DCLD of fine roots under the six treatments could be fitted well by the extreme value function (R2>0.98). The correlation analysis showed that specific root length for roots of 0-1 mm diameter was significantly negatively correlated with the parameter c, and the actual total root length was significantly positively correlated with the parameter b. It was concluded that the root morphology of Chinese fir seedlings would respond to both soil warming, nitrogen addition and their interaction, and these responses could be reflected by the changes in parameters of the extreme value model.

Influence of soil compaction on the growth of silver fir (Abies alba Mill.) under a forest canopy

In the study, the influence of soil compaction on the growth of silver fir seedlings ( Abies alba Mill.) was evaluated; the soil compaction being measured using a cone penetrometer. The studies were conducted under a forest canopy, where the exploratory units with different soil compactions exerting a unit pressure of 50, 100, 150, 200, and 250 kPa, as well as the control units (without pressure), were prepared. Selected units were sown with seeds of silver fir, and from the remaining units, the soil samples were collected and their compaction measured using a cone penetrometer. After 5 months, the seedlings were collected and their growth analyzed. Increasing the unit pressure resulted in soil compaction characterized by the compaction in the layer up to 15 cm, in which the roots of the growing seedlings were found. Different variants of the pressure significantly affected the analyzed parameters of seedlings. Negative and statistically significant correlation was reported between increasing compaction of the soil, the length of the primary root, and the total length of seedlings (-0.46 and -0.35, respectively), while the positive correlation was found for the length of the stem (+0.32). Similarly, there was a statistically significant negative correlation between the increased soil compaction and the dry weight of the root system (-0.29), and positive correlation in the case of the stem dry weight (0.26). Increasing soil compaction, however, did not affect significantly the size of assimilation apparatus.